This invention relates generally to fishing gear such as nets and lobster traps and the like placed in bodies of water and more specifically to apparatus used for allowing whales which may become entangled in such fishing gear to break away before serious damage to the whales occurs.
Entanglement of whales in fishing gear has become a world wide problem causing significant human-caused mortality to such whales through entanglement with passive fishing gear. The problem is especially severe with respect to certain species of whales, such as the Northern Right Whale, an endangered species with only some 300 believed to presently exist.
It is an object of the invention to provide apparatus which can be attached to fishing gear and which will allow an entangled whale to break free before serious injury to the whale can occur.
Briefly described, a whale release device made in accordance with a first embodiment of the invention comprises a cylinder having a bore with a closed end in which is slidably received a piston sleeve having a head formed with a circumferentially extending liquid seal and axially extending elongated sections which in turn define a bore formed with a taper. A rope gripping split sleeve member having radially movable but axially aligned sections and having a matching taper on its outer periphery is received in the tapered bore of the piston sleeve. A rope is inserted between the sections of the split sleeve which in turn is received in the bore of the piston sleeve. To set the device for operation, the piston sleeve along with the rope gripping split sleeve are pushed toward the closed end of the housing bore with the wall of the housing bore applying a radial bias on the piston sleeve which in turn is transferred to the rope gripping split sleeve. As the piston sleeve is pushed inwardly, fluid flows freely through a valve in the head of the piston sleeve. The piston sleeve is provided with tabs extending outwardly from its outer circumference and which are received in an increased diameter portion of the housing bore so that outbound movement of the piston sleeve is resisted. When the rope is pulled, the rope gripping split sleeve is compressed due to the tapers which increases the gripping force on the rope. When sufficient force is exerted on the rope, the piston sleeve moves outwardly creating a partial vacuum and enabled by a metered flow of fluid, i.e., sea water, through the valve until the outer part of the piston sleeve is outside the housing and the axially elongated sections are free to move radially outwardly thereby releasing the force on the split sleeve and in turn on the rope. In a second embodiment, a piston rod carrying a piston head extends inwardly from the piston sleeve and is received through a guide plug into a pressure chamber filled with fluid of a selected viscosity. Fluid is allowed to freely pass in one direction into one side of the chamber through a valve mounted in a piston plug in turn mounted on the piston head. Flow in the opposite direction is metered through a hollow needle providing a metered flow and consequent timed release. Preferably, an interlocking lip and notch are respectively formed in the end face of the piston head and one of the plugs to maintain the piston head in the closed position until a selected force is applied to the rope.
Additional objects and features of the invention will be set forth in part in the description which follows and in part will be obvious from the description. The objects and advantages of the invention may be realized and attained by means of the instrumentality""s and combinations particularly pointed out in the appended claims.